What was found
15 MINUTES INTO THE FLIGHT, THE CREW FELT A SUDDEN VIBRATION ACCOMPANIED BY A ONE SECOND BUZZING SOUND. THE CABIN CREW REPORTED A SERIES OF 3 OR 4 THUDS THAT RESEMBLED SPEED BUMPS FOLLOWED BY A CONSTANT VIBRATION FELT IN THE FLOOR IN THE AFT GALLEY AREA. RETURNED TO ORD WITH THROTTLE IN IDLE. OIL PRESSURE NORMAL. NR 3 FUEL NOZZLE FAILED DUE TO CHEVRON SEAL LEAK. THIS CAUSED 3 (EA) T-2 NGV BURN THROUGH AND RESULTED IN SEVERE DOWN STREAM DAMAGE IN THE N1 TURBINE AND EXHAUST CASE. PART TOTAL CYCLES, 18,652.